While the Opera web browser may not have the largest market share, it is the source off many browser innovations. Tabbed browsing got its start in Opera, and the browser was one of the first to broadly support emerging standards like HTML5 and CSS 3.

We took a detailed look at Opera 10.5 when the first beta was released for Windows and found that, aside from some interface design changes, the big news in this release is speed. This is largely due to the inclusion in this release of Opera’s new Carakan JavaScript engine, which boosts the browser’s performance on webapps considerably. Opera 10.5 is noticeably faster than its predecessors and even beat Firefox 3.6 and Google Chrome in our informal testing.

The second beta release is primarily a slew of bug fixes and doesn’t offer much in the way of new features. Still, if you’ve been enjoying the first beta, this release should make the experience a little more stable. And now Mac users can get into the party as well, though 10.5 beta 2 is unfortunately only available for Windows users. Mac users are only caught up as far as Opera 10.5 beta 1.

Also worth mentioning is that native HTML5 video is working in both Windows and Mac version of Opera 10.5 beta. Opera joins Firefox as the second browser to go with the Ogg Theora codec for native web video.